One thing that makes the day drag is everyone on the run watching everyone on the run hit every obstacle on the run. Unless it's Wipe Out hill where there is in fact, only one obstacle.. have folks watch only a couple to make sure they make it then get back in their trucks and drive. I personally like the "stop to make sure the guy behind you makes it, then keep moving" rule, but there's some flexibility involved depending on what trucks and drivers you have.
And there's nothing worse than a stack-up from someone (even the leader) who stops to watch others, to the point where the run can't proceed because he stopped. So 13 trucks are in a line on Fins after the diving board, only to find that now truck #14 can't even go because there are other trucks in the way. And then 13 drivers need to be found and motivated, so that 13 vehicles can move up, enough for the rest of the run to even do what they all just did before they took a break. Best advice to new leaders is move waaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaay up before stopping, much further than you think. It's only 30 seconds to walk a little more back to the obstacle, but if you stop short and then half your group needs to reposition so the other half can proceed, it's an eternity.